Inorganic oxidizer salt explosive compositions containing particulate paper sheet as a pouring density reducer



United States Patent 3,361,603 INORGANIC OXIDIZER SALT EXPLOSIVE COMPO. SITIONS CONTAINING PARTICULATE PAPER SHEET AS A POURING DENSITY REDUCER George L. Grilfith, Coopersburg, Pa., assignor to Trojan Powder Company, Allentown, Pa., a corporation of New York No Drawing. Filed Sept. 21, 1965, Ser. No. 489,075 12 Claims. (Cl. 14938) This invention relates to explosive compositions of unusually low density and more particularly to explosive compositions comprising an explosive and ground paper as a density reducing agent.

Tenney L. Davis in The Chemistry of Powder and Explosives (1941), pointed out that if the quantity of primary explosive used to initiate the explosion of a high explosive is increase-d beyond the minimum necessary for that result, the velocity with which the resulting explosion propagates itself through the high explosive is correspondingly increased. Eventually, a certain optimum is reached, depending upon the physical phase of the explosive, the width of the column, and the strength of the material which confines it, the particular explosive which is used, and the density of the composition. By proper adjustment of these conditions, it is possible to secure .the maximum velocity of detonation.

Most of these variables are easily adjusted, but optimum density is more difiicult to attain, particularly if a low density is desired. Powdered ammonium nitrate formulations, for instance, generally have a density of the order of 0.9 to 1.1 using the conventional ingredients, including the ammonium nitrate, and a fuel, such as nut meal or Wheat flour. The only material, practically speaking, that is available to reduce the pouring density of explosives is bagasse. Bagasse is a dry carbonaceous material obtained from the drying and grinding of sugar cane, and represents the fibrous material residue after the sugar has been separated. It is rather low in density, and is capable of producing ammonium nitrate powdered formulations having pouring densities of the order of 0.3 to 0.5. Bagasse is, however, a carbonaceous material and therefore a fuel, and it is not possible to use a large amount without upsetting the oxygen balance of the composition, which in turn may disadvantageously affect detonation velocity, and even explosive power.

In accordance with the invention, explosive compositions are provided incorporating ground paper as a density reducing agent. Ground paper is capable of producing even lower densities, on a weight-to-weight basis, than is bagasse, and furthermore, it has a lower carbon content' per unit vweight, and thus larger volumes can be incorporated with a lesser effect on oxygen balance. Explosive compositions containing ground paper can be formulated to pouring densities as low as 0.25, half the densityof a comparable bagasse-containing formulation.

Any type of ground paper can be employed as a densityreducing agent in accordance with the invention. Cellulosebase papers obtained from wood-pulp, cotton, straw or esparto can be employed. Papers made in whole or in part of synthetic fibers can also be employed, such as glass paper, polyvinyl chloride paper, asbestos paper, nylon and other polyamide papers, Orlon (polyacrylonitrile) papers, polypropylene papers, polyethylene papers and polyvinylidene chloride papers.

To the extent that the paper contains carbonaceous material, it will also serve as a fuel, and this carbonaceous content will have to be taken into account in computing oxygen balance of the composition. However, the paper will not normally be employed in replacement for all of the carbonaceous or metal fuel, as will be clear from the following discussion.

While Water-absorbent papers can be used, such as crepe paper, newsprint stocks, Manila paper, kraft paper, chipboard paper, rag paper, cardboard, bond paper, onionskin tissue paper, it is normally preferred to employ a nonwater-absorbent paper, such as parchment paper, wax paper, and glassine paper. Parchment paper is a cellulosebase paper which has been treated with concentrated sulfuric acid or zinc chloride, and thus made waterand grease-proof. Ground parchment paper is the preferred paper for use in the compositions of the invention.

The degree of subdivision of the paper is not critical. It Will usually be found satisfactory to have the particle size of the paper comparable to the size of the particles of the other components of the composition. It is virtually impossible to screen ground paper, but the degree of subdivision can be evaluated in terms of pouring density. Ground papers ranging from 0.02 to 0.15 in pouring density are quite satisfactory, and papers ranging from 0.04 to 0.07 in pouring density are preferred.

The amount of paper employed will depend upon the desired density in the composition. The paper is a densityreducing agent, and its ability to reduce density will of course depend upon the starting density of the explosive formulation. More paper will be required to reduce the density of a dense composition to workable density, of the order of 0.25 to 0.5, than is required for a less dense composition, as will be obvious to any one skilled in this art. Very small amounts of the paper, because of its high bulking volume, are effective to reduce density by a noticeable amount, and as little as 0.25% paper by weight of the formulation can be employed. The maximum amount will depend upon the desired density and upon the extent to which the paper will disturb the oxygen balance of the composition. Usually, oxygen balance is not unduly disturbed by amounts up to approximately 20% by weight of the formulation. Amounts Within the range from about 4 to about 16% by weight of the formulation are preferred.

The paper is effective to reduce the density of explosive compositions of all types, such as powdered explosives, compacted or hard explosives, gels, slurries, and plastic extrudable semi-solid explosives. The explosive formulations containing it can be pelleted, granulated or gelled as may be convenient, according to the intended use.

Explosive compositions normally are formulated with an explosive sensitizer, and preferably with an oxidizer salt, together with a fuel.

Any explosive sensitizer can be employed in the compositions of the invention. A preferred sensitizer, because of its sensitivity and high explosive power, is nitrostarch. Additional sensitizers which can be employed include trinitrotoluene, dinitrotoluene, pentaerythritol tetranitrate, dipentaerythritol hexanitrate, mannitol hexanitrate, sorbitol hexanitrate, sucrose octanitrate, ethylene glycol dinitrate, diethylene glycol dinitrate, trimethyloethanetrinitrate, pentolite (in equal parts by weight mixture of pentaerythritol tetranitrate and dinitrotoluene), cyclonite (RDX, cyclotrimethylene trinitramine), composition B (a composition of up to RDX, up to 40% TNT, and 1 to 4% Wax), cyclotol (composition B without the wax), and tetiyl.

These explosive sensitizers are preferably used with an oxidizer salt to compensate for the oxygen deficiency of the sensitizer. Preferably, the oxidizer employed is an inorganic nitrate. Ammonium nitrate and nitrates of the alkali and alkaline earth metals, such as sodium nitrate, potassium nitrate, calcium nitrate, magnesium nitrate, strontium nitrate and barium nitrate, are exemplary inorganic nitrates. Ammonium nitrate and mixtures of ammonium nitrate and another inorganic nitrate are preferred. Excellent results are obtained with mixtures of ammonium nitrate and alkali metal or alkaline earth 3 metal nitrates, and such mixtures are frequently preferred over ammonium nitrate alone.

As the inorganic oxidizers, there can also be used, alone or in admixture with the nitrate, a chlorate or a perchlorate of an alkali or alkaline earth metal, such as sodium chlorate, potassium chlorate, barium chlorate, sodium perchlorate, potassium perchlorate, barium perchlorate and calcium perchlorate. Mixtures of nitrates, chlorates and perchlorates, of nitrates and chlorates, of nitrates and perchlorates, and of chlorates and perchlorates, can be used.

When mixtures of ammonium oxidizer and another oxidizer are used, the relative proportion of ammonium oxidizer is important for good explosive shock and power. The ammonium oxidizer is employed in a proportion within the range from about 50 to 95% by Weight of the total oxidizer, and the other oxidizer or oxidizers is used in the proportion of from about 5 to about 50% of the total oxidizer. For optimum power, the proportions are from 80 to 90% ammonium oxidizer, and from to 20% of the other oxidizer, or oxidizers. The proportions of oxidizer selected within these ranges will depend upon the sensitivity and explosive effect desired, and these, in turn, are dependent upon the particular oxidizer used.

The inorganic oxidizer can be fine, coarse, or a blend of a fine and coarse materials. Mill and prill inorganic oxidizers are quite satisfactory. For best results, the inorganic oxidizers should be fine-grained.

The relative proportions of oxidizer and explosive sensitizer will depend upon the sensitivity and explosive power desired, and these, in turn, are dependent upon the particular oxidizer and explosive sensitizer. For optimum effect, the oxidizer is used in an amount within the range from about 10 to about 75%, and the explosive sensitizer in an amount within the range from about 5 to about 20% by weight of the explosive composition. From about 25 to about 30% explosive sensitizer, and from about 50 to about 70% oxidizer, give the best results.

In addition to these materials, the explosive compositions of the invention can include a fuel, which can be either a metal fuel or a carbonaceous fuel, in an amount of from about 0.5 to about 30%. As indicated above, the amount of paper is taken into account in computing the fuel proportion within the stated range, according to its carbon content. Satisfactory metal fuels include aluminum, which can be in the form of powder or flake, or 'm a very finely-divided form known as atomized aluminum, ferrosilicon and ferrophosphorus. The metal fuel will usually comprise from about 0.5 to about by weight of the composition.

A carbonaceous fuel can also be included, in addition to the paper, with or without a metal fuel. Satisfactory carbonaceous fuels include powdered coal, petroleum oil, coke dust, charcoal, bagasse, dextrin, starch, wood-meal, wheat flour, bran, pecan meal and similar nut-shell meals. The carbonaceous fuel will usually be used in an amount within the range from about 0.5 to about including the carbon content of the paper.

Mixtures of carbonaceous fuel can be used, as well as mixtures of metal fuels, if desired.

Stabilizers can be included in an amount within the range from about 0.3 to about 2% of the composition. Zinc oxide, calcium carbonate, aluminum oxide and sodium carbonate are useful stabilizers.

The paper employed as a density reducer in accordance with the invention also can be employed in explosive slurries, using an inert liquid such as water or petroleum oil as the suspending liquid. Such slurries will contain the same types of components described above, with enough liquid to produce a slurry, in excess of the amount of liquid that would be absorbed by the solid ingredients. The slurry can have any desired consistency, from a thin readily-fiowable material to a viscous material of a semisolid consistency. As little as 0.5% liquid may suffice. Usually, not more than 30% liquid need be used.

In order to prevent large amounts of unabsorbed liquid from decreasing the consistency unduly, a liquid-soluble or liquid-dispersible thickener can be added to take up the liquid. The particular materials employed will depend upon the liquid that is used, water-soluble or waterdispersible thickeners being used when water is the liquid, and oil-soluble or oil-dispersible thickeners being used when an oil is the liquid. Various gums, such as guar gum and cross-linked guar gum, can be used, as well as carboxymethyl cellulose, methyl cellulose, psyllium seed mucilage, and pregelatinized starches, such as Hydroseal 3B, as well as silica aerogels, finely-divided silicas, inorganic gelling agents such as alumina, attapulgite, bentonite, and like materials.

The explosive mixture is readily prepared by simple mixing of the ingredients. In the case of slurries, gels and semi-solid formulations, it is usually desirable to mix the solid materials to form a homogeneous blend, and then any liquid ingredient such as oil and water would be added, with stirring until a homogeneous mixture is formed. A thickening agent can be incorporated in advance with the oil and/or water, or mixed with the solid ingredients, as desired.

These explosive compositions can be filled into explosive containers of any type, using conventional filling equipment suited to the particular consistency of the composition. A plastic composition is readily extruded into the containers, while a powdered, granulated or pelleted formulation is conveniently filled by conventional screw fillers.

The following examples in the opinion of the inventor represent the best embodiments of his invention.

Examples 1 and 2 A dry powdered formulation based on ammonium nitrate and fuel oil was prepared, using grained mill ammonium nitrate, nut meal, petroleum oil, and ground parchment paper in accordance with the invention. A formulation was prepared without the ground parchment paper, and one with bagasse, as controls, to observe the differences in density. In each case, the dry ingredients were thoroughly blended in a mixer. The proportions of the final explosive compositions were as follows:

The pouring densities of each of these compositions was determined, and the explosive power evaluated in terms of ballistic pendulum value, using a No. 16 blasting cap. The following data was taken:

Control Control Example Example Pouring density 0.73 0. 420 0.350 0. 370 Ballistic pendulum value 12. 1 11. 6 11. 9 11. 9

It is evident from the above results that the ground parchment paper (1 and 2) gives a formulation having a lower density than bagasse (Control B) for an equal weight, and a slightly better ballistic pendulum value. The improvement in density as compared to Control A without the bagasse is also evident from the data, and it is apparent from the ballistic pendulum values that this improvement is obtained without significant deleterious effect on explosive power.

Example 3 Powdered nitrostarch-bagasseommonium nitrate explosive formulations were prepared, including flake alumimum and rifile coal a's fuels, with wheat flour or ground parchment paper as density reducing agents. The dry ingrc'dients were thoroughly mixed in a mill-type mixer, to the following formulations:

The pouring density of each of these compositions was determined, together with the D-sensitivity and ballistic pendulum values. The D-sensitivity was determined in a steel pipe, 1%, x 8 inches, and the ballistic pendulum value was determined using a No. 16 blasting cap. The following data was taken:

Control Example 3 Standard Pouring Density 1. 44 1. 32 D-Sensitivity No. 8/10 cap No. 2 cap Ballistic Pendulum Value 11. O 11.

It is apparent from the data that the parchment paper gave a considerably reduced density, and an increased sensitivity, as compared to wheat flour. The increase in sensitivity is due to the decrease in density.

Examples 4 to 7 A group of nitrostarch/ammonium nitrate-based powdered explosives was prepared, in accordance with the procedure of Example 2, to the following formulation:

Percent by Weight Ingredients Ex. 4 Ex. 5 Ex. 6 Ex. 7

Nitrostarch (dry). 13. 00 13. 00 13.00 13.00 N itrostarch (wet) 1. 00 1. 00 1. 00 1. 00 Ammonium nitrate, grained mill. 75. 34 75. 34 75. 34 75. 34 Sodium nitrate 2. 00 2. 00 2. 00 2. 00 Zinc oxide 0. 0. 10 0. l0 0. 10 Flake aluminum. 2. 75 2. 75 2. 75 2. 75 Nut me 3. 50 3. 50 Bagasse 2 00 2. O0 Petroleum oil 0.30 0.30 0 30 0.30 Ground parchment pape 0.055 pouring density 3.50 2. 00 0.053 pouring density 3. 50 2 00 Carbon black 0. 01 0. 01 O. 01 0. 01

The standard pouring density of these formulations was determined, together with D-sensitivity in steel pipe 1% x 8 inches. The ballistic pendulum value was determined using a No. 6 blastin cap. The following data was taken:

Example 4 Example 5 Example 6 Example 7 Standard pouring density 1.040 1.025 1. 145 1. D-Sensitivlty No. 1 cap No. 1 cap N o. 2 cap N o. 2 cap Ballistic pendulum value, No. 6 cap 11.8 11.9 11.7 11.9

It is evident from the above that when added to a composition already containing bagasse, the ground parchment paper is eflfective in producing a composition of considerably lower density (Examples 4 and 5). 2% ground parchment paper (Examples 6 and 7) alone is also effective in reducing density.

Example 8 A nitrostarch/ ammonium nitrate-based powdered explosive was prepared, in accordance with the procedure of Example 2, to the following formulation:

Ingredients: Percent by weight The standard pouring density of this formulation was determined, together with the D-Sensitivity in a steel pipe 1% x 8 inches. The ballistic pendulum value was determined using a No. 6 blasting cap. The following data was taken:

Standard pouring density 1.220 D-Sensitivity N0. 1 cap Ballistic pendulum value, No. 6 cap 10.85

In the specification and claims, all percentages are by weight of the composition, and all densities are in metric units, g./cc.

I claim:

1. An explosive composition consisting essentially of an inorganic oxidizer salt, and a member selected from the group consisting of nitrated organic sensitizers, carbonaceous fuels, metallic fuels and mixtures thereof and an amount of particulate thin paper sheet sufficient to lessen the pouring density of the composition.

2. An explosive composition in accordance with claim 1, in which the sensitizer is nitrostarch.

3. An explosive composition in accordance with claim 1, in which the sensitizer is trinitrotoluene.

4. An explosive composition in accordance with claim 1, in which the inorganic oxidizer is an inorganic nitrate.

5. An explosive composition in accordance with claim 4, in which the inorganic nitrate is ammonium nitrate.

6. An explosive composition in accordance with claim 4, in which the inorganic nitrate is a mixture of ammonium nitrate and an inorganic nitrate selected from the group consisting of alkali and alkaline earth metal nitrates.

7. An explosive composition in accordance with claim 1, consisting essentially of a nitrated organic sensitizer in an amount from about 5 to about 40 percent by weight, an inorganic nitrate oxidizer salt in an amount from about 10 to about 75 percent by weight, and a metallic or carbonaceous fuel.

8. An explosive composition in accordance with claim 7, in which said member is a metal fuel.

9. An explosive composition in accordance with claim 7, in which said member is a carbonaceous fuel.

10. An explosive composition in accordance with claim 1, in which the paper is cellulose-base paper.

11. An explosive composition in accordance with claim 10, in which the paper is parchment paper.

12. An explosive composition in accordance with claim 1, in which the paper has a pouring density Within the range from about 0.02 to about 0.15.

References Cited UNITED STATES PATENTS 1/1927 Marshall 14947 X 8 Ba slrford 149--46 X Taylor 149-112 X Williams 149-412 X Griffith et 'al. 149-62 X Schulz 14919 X Examiners.

S. J. LECHERT, IR., Assistant Examiner. 

1. AN EXPLOSIVE COMPOSITION CONSISTING ESSENTIALLY OF AN INORGANIC OXIDIZER SALT, AND A MEMBER SELECTED FROM THE GROUP CONSISTING OF NITRATED ORGANIC SINSITIZERS, CARBONACEOUS FUELS, METALLIC FUELS AND MIXTURES THEREOF AND AN AMOUNT OF PARTICULATE THIN PAPER SHEET SUFFICIENT TO LESSEN THE POURING DENSITY OF THE COMPOSITION.
 7. AN EXPLOSIVE COMPOSITION IN ACCORDANCE WITH CLAIM 1, CONSISTING ESSENTIALLY OF A NITRATED ORGANIC SENSITIZER IN AN AMOUNT FROM ABOUT 5 TO ABOUT 40 PERCENT BY WEIGHT, AN INORGANIC NITRATE OXIDIZER SALT IN AN AMOUNT FROM ABOUT 10 TO ABOUT 75 PERCENT BY WEIGHT, AND A METALLIC OR CARBONACEOUS FUEL.
 8. AN EXPLOSIVE COMPOSITION IN ACCORDANCE WITH CLAIM 7, IN WHICH SAID MEMBER IS A METAL FUEL. 